binary_size: Check debug data format before starting.

tools/binary_size/run_binary_size_analysis.py

Index: tools/binary_size/run_binary_size_analysis.py
diff --git a/tools/binary_size/run_binary_size_analysis.py b/tools/binary_size/run_binary_size_analysis.py
index 7647a22dcb69b351b429f0e6e35911dd39e1b8be..ab93ecfc5a100c5c1cabb80b97c405fdc3733544 100755
--- a/tools/binary_size/run_binary_size_analysis.py
+++ b/tools/binary_size/run_binary_size_analysis.py
@@ -544,6 +544,34 @@ def _find_in_system_path(binary):
       return binary_path
   return None
 
+def CheckDebugFormatSupport(library, addr2line_binary, nm_binary):
+  """There are two common versions of the DWARF debug formats and

[Primiano Tucci (use gerrit), 2014/05/27 09:40:10]

Nit: docstring format (1 line + blank line + description)

[Daniel Bratell, 2014/06/04 13:31:02]

Done.

+  since we are right now transitioning from DWARF2 to newer formats,
+  it's possible to have a mix of tools that are not compatible. Detect
+  that and abort rather than produce meaningless output."""
+  tool_output = subprocess.check_output([addr2line_binary, "--version"])
+  version_re = re.compile(r"^GNU [^ ]+ .* (\d+).(\d+).*?$", re.M)

[Primiano Tucci (use gerrit), 2014/05/27 09:40:10]

Please be consistent with quotes (double vs single)

[Daniel Bratell, 2014/06/04 13:31:02]

Done.

+  parsed_output = version_re.match(tool_output)
+  major = int(parsed_output.group(1))
+  minor = int(parsed_output.group(2))
+  supports_dwarf4 = major > 2 or major == 2 and minor > 22
+
+  if supports_dwarf4:
+    return
+
+  print("Checking version of debug information in %s." % library)
+  debug_info = subprocess.check_output(["readelf", "--debug-dump=info",
+                                       "--dwarf-depth=1", library])
+  dwarf_version_re = re.compile(r"^\s+Version:\s+(\d+)$", re.M)
+  parsed_dwarf_format_output = dwarf_version_re.search(debug_info)
+  version = int(parsed_dwarf_format_output.group(1))
+  if version > 2:
+    print("""\

[Primiano Tucci (use gerrit), 2014/05/27 09:40:10]

From code style:

Yes:
  print ("This is much nicer.\n"
         "Do it this way.\n")
  No:
    print """This is pretty ugly.
Don't do this.
"""

[Daniel Bratell, 2014/06/04 13:31:02]

Will fix, but the suggested format is really bad if the indentation plus the
string length would exceed ~70 characters. In another program I've tried both
and I found that for larger blocks of output, the """ format worked better.
Especially if the first line is """\ so that all lines are indented equally.

+The supplied tools only support DWARF2 debug data but the binary
+uses DWARF%d. Update the tools or compile the binary with -gdwarf-2.""" %
+          version)
+    sys.exit(1)
+
 
 def main():
   usage = """%prog [options]
@@ -638,8 +666,10 @@ def main():
     assert nm_binary, 'Unable to find nm in the path. Use --nm-binary '\
         'to specify location.'
 
-  print('nm: %s' % nm_binary)
   print('addr2line: %s' % addr2line_binary)
+  print('nm: %s' % nm_binary)
+
+  CheckDebugFormatSupport(opts.library, addr2line_binary, nm_binary)
 
   symbols = GetNmSymbols(opts.nm_in, opts.nm_out, opts.library,
                          opts.jobs, opts.verbose is True,